In the packaging of many liquid household products, e.g., window cleaners, insect poisons, cleaning fluids, etc., it has been found market-attractive to include, as part of the package, a finger actuated dispensing pump. These pumps are generally fitted with nozzles which are capable of product delivery in a spray mode and/or a stream mode. Most nozzles produce the spray mode by causing the liquid product to be broken up into small particles as it is dispensed in a vortical state from the nozzle. The desired vortex is generally formed by forcing the liquid to traverse, while under pressure, a swirling path as the liquid exits the nozzle outlet orifice. The swirling path can b accomplished by the use of any of the well known "swirl chamber" devices which are associated with the nozzle. See for example the devices of U.S. Pat. Nos. 4,358,057; 4,257,751; and 4,161,288.
The spray mode of delivery is preferred over the stream mode in those applications where the product is to be applied evenly over a relatively large area. However, due to the break-up of the liquid, some of the product will be delivered as a fine mist. Also a fine mist can be formed when the product impacts the surface on which it is sprayed. When the product is applied in an enclosed area, e.g., a shower stall, there is the possibility that the user will inhale some of the mist. Thus, the spray mode of delivery, while useful in many applications, is not always desirable.
To overcome the problems created by the fine mist, the pump industry has developed a foam mode of delivery. To achieve foaming of the dispensed product, the nozzles provide for aeration of the product after it leaves the swirl chamber. This aeration can be effected by aspirating air into the nozzle so that the air is entrapped in the small particles of product which have been produced by the swirl chamber. While the foam mode of delivery minimizes the production of the fine mist and is thus desirable for certain applications, the area of coverage achieved by foam delivery is less than the area of coverage which is achievable by the spray delivery. Therefore, as is the case for spray delivery, foam delivery is desirable in many applications but not in all applications.
Since the use of many products dictates the use of spray delivery in some applications and foam delivery in other applications, there is a need for a nozzle which can selectively provide spray delivery or foam delivery. It is therefore an object of this invention to provide such a nozzle.